Microprocessor is a ULSI (Ultra Large Scale Integration) which contains 1 million transistors, which drive everything from computer in the world of personal computers, the terms microprocessor and CPU are used interchangeably. At the heart of all personal computers and most workstations sits a microprocessor.
Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.
Three basic characteristics differentiate microprocessors:
(a) Instruction set: The set of instructions that the microprocessor can execute.
(b) Bandwidth: The number of bits processed in a single instruction is termed as bandwidth.
(c) Clock speed: The instruction speed is measured on the basis of clock speed. The clock speed determines how many instructions per second the processor can execute.
In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that executes at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHZ.
Some of the microprocessors are listed below:
(a) 8-bit Microprocessor: 8008 was the first microprocessor chip.
(b) 16-bits Microprocessor: IMP-16 was the first multi-chip 16 bits microprocessor, designed by National Semiconductor and first single 16-bit microprocessor, PACE, was designed by National in 1975.
(c) 32-bit Microprocessor: BELLMAC-32A was the first 32-bit single chip microprocessor.
The origin of microprocessors can be traced back to Ted Hoff working with Intel Corporation, USA, in the late sixties. Hoff was fascinated by the idea of integrated circuits- complete electronic on a chip. Actually, he wanted to place entire CPU of a computer on a chip. The idea, approved and implemented by Federico Faggin of Intel Corporation, resulted in the first marketed microprocessor, the Intel 4004 followed by the 8008 in 1974.
Altair 8800 was the first microcomputer designed by Ed Robert, president of MIT. This based on the modified version of Intel 8008 microprocessor chip, known as 8080. The Altair had a memory of 1K characters.